Member
Joined 2003
sharpi31 said:I emailed Class-D two days ago asking for instructions for setting bias. When I get an answer I will post it here
Tried to phone you on a number of accasions phone is turned of email me Mike@class-d.com when you are available or call 0044 7980 600373.
I will then tell you how to set it up.
Actually everyone that is built is preset on a scope for minimum crossover distortion at 20 khz a little over the top most set it at 1 khz but what the heck
I had a good chat with Mike from Class-D last night. He struck me as a decent guy with a passion for his amp modules. Mike asked me to call him if I had any issues - he seemed genuinely keen to help me in any way he could.
Mike reiterated that they set bias for minimum crossover distortion at 20KHz on all modules in the factory. He also explained that I could check/tweak the bias using a 20KHz tone on the input and dummy load and scope on the output.
I plan on assembling the amp 'as supplied' and I'll give it a listen without checking bias. Then I'll have a good idea of how the amp sounds out-of-the-box. I'll check bias when I tweak the amp with new PSU, coupling and feedback caps - then I can compare 'as supplied' with 'heavily modded'.
My gf is away tomorrow so I should have a clear run at assembling the amp. Wish me luck!
Mike reiterated that they set bias for minimum crossover distortion at 20KHz on all modules in the factory. He also explained that I could check/tweak the bias using a 20KHz tone on the input and dummy load and scope on the output.
I plan on assembling the amp 'as supplied' and I'll give it a listen without checking bias. Then I'll have a good idea of how the amp sounds out-of-the-box. I'll check bias when I tweak the amp with new PSU, coupling and feedback caps - then I can compare 'as supplied' with 'heavily modded'.
My gf is away tomorrow so I should have a clear run at assembling the amp. Wish me luck!
S
spitzer
NX200 first impressions
I just finished assembling the amp, and successfully managed to resist the temptation to modify the NX200 module. I even used the designated signal input point so that the onboard 22uF ceramic(?) coupling cap is in the signal path.
I used a 41V transformer which gives me 65V rails, a Vishay 35A bridge rectifier (with 0.01uF Wima FKP bypasses), 2x10000uF BHC slit foil per rail. To match my UCD180HG power amp I used Neutrik Speakons, Powercon & insulated phono sockets (so swapping from one to the other couldn't be easier).
I just finished assembling the amp, and successfully managed to resist the temptation to modify the NX200 module. I even used the designated signal input point so that the onboard 22uF ceramic(?) coupling cap is in the signal path.
I used a 41V transformer which gives me 65V rails, a Vishay 35A bridge rectifier (with 0.01uF Wima FKP bypasses), 2x10000uF BHC slit foil per rail. To match my UCD180HG power amp I used Neutrik Speakons, Powercon & insulated phono sockets (so swapping from one to the other couldn't be easier).
Attachments
I'm listening to the amp with the following system: Behringer SRC2496 (passive output with sowter transformers), diy grounded grid preamp & Rogers LS5/9 speakers.
After a quick blast of Roots Manuva, John Martyn & BBC radio 3 I'm pretty impressed. Bass is deep, powerful and well defined. Mids are smooth. HF is slightly brittle but well resolved - lots of detail but not very sweet. The soundstage seems a bit further back than the UCD amp, but is deep and broad and the amp delivers plenty of atmosphere (lots of resonance where appropriate).
My preamp has capacitor coupled outputs so I can bypass the 22uF ceramics. Given the slight brittleness of the HF this will be my first change. Then it'll be PSU and feedback caps ;-)
As supplied, these modules are great for £40. As it stands, this amp won't be replacing my UCD - in my system the Hypex amp is more dynamic and has a sweeter top end. It's pretty close though, and I'm sure that it'll be even closer after the nasty ceramic cap is bypassed.
After a quick blast of Roots Manuva, John Martyn & BBC radio 3 I'm pretty impressed. Bass is deep, powerful and well defined. Mids are smooth. HF is slightly brittle but well resolved - lots of detail but not very sweet. The soundstage seems a bit further back than the UCD amp, but is deep and broad and the amp delivers plenty of atmosphere (lots of resonance where appropriate).
My preamp has capacitor coupled outputs so I can bypass the 22uF ceramics. Given the slight brittleness of the HF this will be my first change. Then it'll be PSU and feedback caps ;-)
As supplied, these modules are great for £40. As it stands, this amp won't be replacing my UCD - in my system the Hypex amp is more dynamic and has a sweeter top end. It's pretty close though, and I'm sure that it'll be even closer after the nasty ceramic cap is bypassed.
The case is from RS in the UK and costs only £22
RS diecast aluminium box 250x250x100mm
It gets quite hot to the touch, but you can hold your hand flat on the panel with the mosfets attached for as long as you like (so it isn't that hot really). I haven't played with bias yet so it may yet get hotter or cooler...
Planning to use Rubycon ZLH for PSU caps.
RS diecast aluminium box 250x250x100mm
It gets quite hot to the touch, but you can hold your hand flat on the panel with the mosfets attached for as long as you like (so it isn't that hot really). I haven't played with bias yet so it may yet get hotter or cooler...
Planning to use Rubycon ZLH for PSU caps.
S
spitzer
Nice, fair, sane, thanks please more. Moderator deleting relevant question and member aliking then encourage more off topic content to pollutoining d forum. What nice fair in sane and that. Can four birds squeeking be full chorus. Rest of thousand who not so fooled easily thinking to this can be at cost of deletion for self in history rewrite of moderator, can no disagree.
Consistant for theme to all bogus class d thread, sucking blood from lore of ucd that war hardend proven. Telling what you expecting to find true, make you easy believer, clapping and giggle, mystified. Rest having say nothing or get delete, nice, fair, sane, yes thanks more, making sick form.
Comparative review that faking comparition, standing who benefit from just implying equivalent to proven. Where is even contestant? Only implied leaving to imagition UCD, all to lore. So to concluding it sound almost same before tweaking, no heatsinking needed that crazy but to prove market lie can be true, saying "nice guy keen for
service", "good for so cheap in comparing". Sane comparition, this only PR tricking.
Maybe thinking too much cost in saying better, and can no with piezo coupling. Next to come, tweaking finish, this now daily cook, still cheaper, now better, thanking to mr so nice for so cheap so good. I still not believing one true come for so many none. Not before tweak and not after tweak.
Where is picture of ucd build and is wired like best said to be or to just having work? Is even having ucd? Will also bypass ucd coupling, ceramic to film is one, DC to film different to, making real announced expectation another still it can be.
Not to forgetting using piezo speaking component coupling having no place in good audio, rest of part in other place can be no better from same selector, picture already telling they cheapest can be. Selling knowing good part maybe lipstick on pig. That all fine to OK for cheap thing when selling as cheap thing, to make believe after it can be as real good thing then believing breaking down.
Comparition making to look same for sane fair, same connector type maybe not same wiring maybe not so good it not shown, same type cap not same rating, no looking to transformer with twice power can make no difference. Still 180 more dynamic? For now before tweaking. Still have to add heat sink in real amp and for worser case, no point for ommission but in proving what say marketing. Keeping hand for some second not make amp long lifetime for cheap part it build from when high heating.
Seeming eager for reviewing for PR, that even allow no time for cap to form. No giggle like baby to me when in few day you back saying what predict new favorite. Sorry no can believing. Nothing in deleted history sane to fair so far no mattering how loud clap. Can't even real enough for play own court when there identical amp that already tweak and better for right rating and not silly efficient class d name for marketing. Compare to it. Laws not even allowing these deceipt, only tweaked forum that delete objectivity when hurts marketing lie. So sane people seeing still, this no interesting to them but to call for how see is real.
Consistant for theme to all bogus class d thread, sucking blood from lore of ucd that war hardend proven. Telling what you expecting to find true, make you easy believer, clapping and giggle, mystified. Rest having say nothing or get delete, nice, fair, sane, yes thanks more, making sick form.
Comparative review that faking comparition, standing who benefit from just implying equivalent to proven. Where is even contestant? Only implied leaving to imagition UCD, all to lore. So to concluding it sound almost same before tweaking, no heatsinking needed that crazy but to prove market lie can be true, saying "nice guy keen for
service", "good for so cheap in comparing". Sane comparition, this only PR tricking.
Maybe thinking too much cost in saying better, and can no with piezo coupling. Next to come, tweaking finish, this now daily cook, still cheaper, now better, thanking to mr so nice for so cheap so good. I still not believing one true come for so many none. Not before tweak and not after tweak.
Where is picture of ucd build and is wired like best said to be or to just having work? Is even having ucd? Will also bypass ucd coupling, ceramic to film is one, DC to film different to, making real announced expectation another still it can be.
Not to forgetting using piezo speaking component coupling having no place in good audio, rest of part in other place can be no better from same selector, picture already telling they cheapest can be. Selling knowing good part maybe lipstick on pig. That all fine to OK for cheap thing when selling as cheap thing, to make believe after it can be as real good thing then believing breaking down.
Comparition making to look same for sane fair, same connector type maybe not same wiring maybe not so good it not shown, same type cap not same rating, no looking to transformer with twice power can make no difference. Still 180 more dynamic? For now before tweaking. Still have to add heat sink in real amp and for worser case, no point for ommission but in proving what say marketing. Keeping hand for some second not make amp long lifetime for cheap part it build from when high heating.
Seeming eager for reviewing for PR, that even allow no time for cap to form. No giggle like baby to me when in few day you back saying what predict new favorite. Sorry no can believing. Nothing in deleted history sane to fair so far no mattering how loud clap. Can't even real enough for play own court when there identical amp that already tweak and better for right rating and not silly efficient class d name for marketing. Compare to it. Laws not even allowing these deceipt, only tweaked forum that delete objectivity when hurts marketing lie. So sane people seeing still, this no interesting to them but to call for how see is real.
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